1. Field of the Invention
The present invention relates to a light emitting diode (LED) driving apparatus. More specifically, the present invention relates to an LED driving apparatus that supplies power to an LED load and other load.
2. Description of the Related Art
There has been proposed an LED driving apparatus that drives a plurality of LEDs connected in series (for example, refer to JP-A-2004-319583).
According to the LED driving apparatus disclosed in JP-A-2004-319583, a plurality of LED load groups (LED strings), each of which has a plurality of LED devices connected in series, is connected in parallel. However, since the LED devices have different forward voltages Vf, respectively, when they are driven with the LED load groups being connected in parallel, currents flowing in the respective LED load groups are unbalanced. Accordingly, in JP-A-2004-319583, constant current circuits corresponding to each of the LED load groups are provided to control the currents flowing in each of the LED load groups, thereby balancing the currents flowing in the LED load groups.
However, according to the related-art LED driving apparatus, the constant current circuits are required in correspondence to the parallel number of LED load groups, so that the LED driving apparatus is enlarged and the cost thereof is increased. Furthermore, the related-art LED driving apparatus has not considered supplying power to other load in addition to the LED loads.